But Nunes, R-California, said he is not confident the U.S. will be able to track all 250, despite the fact that the FBI has opened an investigation in all 50 states to find these Americans. He is also concerned that those who have left can return to the United States.

Earlier this month, the Pentagon confirmed to ABC News that it is investigating allegations that Centcom’s intelligence on ISIS was distorted to provide a more positive picture.

Nunes, who also said he believed the White House’s current policy on fighting ISIS will not succeed, indicated that he believed those allegations to be true.

It has been "alarming," Nunes said, to look at the intelligence on the ground in Syria and compare it with the way the fight against ISIS is being portrayed by the White House.

"When you look at the final product and what the president has been saying, you look at the policies he's been implementing, it really makes me wonder, is it the analysts getting the information wrong or is it being politicized?" he said.